[minism]

I haven't looked at the game implementation in detail yet, but in order to verify "This person has found the treasure" is signed with the key for coordinates (X,Y), we need to know the cooresponding public key for coordinates (X,Y), which means that youre revealing the coordinates themselves in your message.

The idea in ZKP is to prove you know a value without revealing the value itself.

[aib]

I don't know how actual asymmetric KDFs work, but I was thinking more along the lines of secret -> private key -> public key, i.e. the public key doesn't contain information about the secret.